As always, the All-Star rosters don't reflect first half performance. Here is the American League roster that should be taking the field in New York. In the interest of science, sabermetrics, and correcting things that should be there in the first place, I have ignored the "every team must be represented" rule. Starters are listed in italics, asterisks designate injured players.
As much as I love Perez, Santana has been far better offensively this season. He has a .361 wOBA and 132 wRC+ compared to Perez's .329 wOBA and 107 wRC+. His 14.8% walk rate dwarfs Perez's 3.0% and is why Santana's OPS is nearly 80 points higher. Santana also has more home runs (10 to 4) and RBI (38 to 36). Perez makes up ground defensively, and it shows in their similar fWAR values (Santana at +1.9, Perez at +1.7).
Meanwhile, Mauer and Castro join Santana in what has been a "big three" of American League catchers this year. Castro's .804 OPS, .345 wOBA, and 119 wRC+ all rank third among AL catchers with at least 200 plate appearances. Mauer is first in all three categories, and Santana is second.
Top performers: Davis, Edwin Encarnacion (Blue Jays)
You could go with any one of Encarnacion, Adam Lind, or James Loney as Davis' backup, but Lind missed some time due to injury. As for Encarnacion vs. Loney, I give Encarnacion points for hitting for a much higher slugging average and for having more sustainable numbers. Encarnacion has a .526 slugging average and .260 ISO compared to Loney at .478 and .158, respectively. Meanwhile, his line drive rate isn't approaching 30% like Loney's.
Chris Davis has a slugging average of .717 and an ISO of .392. Video games are too hard now to call those "video game numbers," so I don't even know what to call them besides "really good."
Top performers: Cano, Kipnis, Pedroia, Howie Kendrick (Angels)
Four second basemen seems a bit excessive, but they did it on the actual roster and Ben Zobrist has been crap this year (more on that below). Kendrick has put up the quietest career year of 2013 thus far, hitting .317/.360/.473 with 10 home runs, a .357 wOBA, and a 130 wRC+. His line drive rate is nearly as high as Loney's, but he doesn't have a competitor neck-and-neck with him like Loney did.
The bigger debate here is who deserves to start. Pedroia and Kipnis are neck-and-neck in WAR, with Pedroia getting the love from defensive metrics to make up for Kipnis' superior offensive numbers. Given the volatility of advanced defensive statistics and Kipnis' white-hot bat in June, he gets the nod. Meanwhile, Robinson Cano is good enough to see his stats regress across the board and still be a lock for the roster.
Top performers: Peralta, Yunel Escobar (Rays)
I debated listing only Peralta on this list, but Escobar's defensive stats were impressive enough to garner a nod at the most important defensive position in the infield. His .301 wOBA and 92 wRC+ are slightly more medicore than Hardy's .313 wOBA and 98 wRC+, but Hardy has nine more home runs than Escobar. Someone with 15 home runs in 87 games should be at least a league average hitter. Defensively, Escobar's glove has been better. Instead of an awkwardly worded sentence comparing their respective numbers (because there's plenty of those in this post), here's a table.
Jed Lowrie's offensive numbers are better than both Hardy's and Escobar's, but his glove has been absolutely brutal at short this season. While defensive statistics can be volatile from year to year, Lowrie's glove has been consistently below average at short over the past five seasons, so it's not that outrageous to think that he's becoming more exposed as he spends more time at the position.
Top performers: Cabrera, miles of empty space on a page, Machado, Evan Longoria (Rays)
Three third basemen? I do what I want. I'm shocked that Longoria was snubbed in favor of teammate Ben Zobrist, especially when you consider that Longo is on pace for his best season as a big leaguer. His glove has been nearly as elite as Machado's, but his bat has been much better. Machado's doubles frenzy has been impressive, but advanced metrics aren't a fan of his lack of power (.161 ISO) and horrible walk rate (4.0%). Still, he's too good to keep off this roster.
Top performers: Trout, Bautista, Jones, Cruz, Gordon, Jacoby Ellsbury (Red Sox)
Mike Trout? Garbage defender. At least that's what Fangraphs seems to think. The lack of wall-climbing catches are the main reason for Trout's defensive "drop off," but the offensive numbers are just as astounding as they were in 2012. Bautista has been good enough to put up a .375 wOBA and 138 wRC+ despite a .264 batting average. Jones' numbers (WAR, in particular) have been hurt by unfavorable defensive metrics even more than Trout's.
The real debate here is what to do with that sixth outfield spot. Hunter has been good this year, but I don't see anything that separates him from the pack. Austin Jackson would have been a lock for the roster had he not gotten hurt, so I went with the next best option in Ellsbury. He is third in the AL among outfielders with 3.1 fWAR and leads the majors with 36 stolen bases. His glove has been above average, as usual. Aside from the lack of home runs, he has been every bit of the player that finished second in the 2011 MVP race.
Top performers: Ortiz, Josh Donaldson (A's)
Donaldson is a third baseman, but the position is too stacked to list him there. That said, he has been too good in the first half to snub him from the roster. He is hitting .317/.385/.533 with 15 home runs this year, and his .393 wOBA and 154 wRC+ are much higher than just about anyone else that could have filled in at this position. Sure, Miguel Cabrera might be a more appropriate DH in theory, but both he and Big Papi have earned the starting nod.
Top performers: Don Ke- just kidding
Zobrist is technically listed as a second baseman, but as usual, Joe Maddon has penciled him in all over the diamond. He has started 55 games at second base, 22 in right field, and four at shortstop this season. Over the past five seasons, he has played every position on the diamond besides catcher.
That said, Zobrist's numbers have taken a big hit this season. He is only hitting .260/.348/.376 with five home runs. His .322 wOBA and 107 wRC+ are both 10th among American League second basemen. In his other All-Star season (2009), Zobrist had 17 home runs, 11 steals, and a 1.012 OPS in the first half.
Actually going: Clay Buchholz (Red Sox), Bartolo Colon (Athletics), Yu Darvish (Rangers), Felix Hernandez (Mariners), Hisashi Iwakuma (Mariners), Justin Masterson (Indians), Chris Sale (White Sox), Max Scherzer (Tigers), Justin Verlander (Tigers)
If we're going to include Clay Buchholz on the All-Star roster despite only pitching 84 1/3 innings this season, then Sanchez has to make the team. Both have been outstanding this season despite the time missed due to their respective injuries, and the numbers are too gaudy to ignore. Sanchez has a 2.11 FIP to to Buchholz's 2.49, a 2.80 SIERA to Buchholz's 3.47, and the second-best strikeout rate in the league.
Holland deserves the nod over Bartolo Colon due to superior peripheral statistics and a much more hitter-friendly home ballpark. Colon's home/road splits are nearly even, but there's something to be said about Holland maintaining a 3.35 ERA in Arlington.
What about other deserving pitchers? James Shields has put up a couple of stinkers recently that hurt his numbers. Our very own Justin Verlander and Doug Fister have nice peripherals, but their actual production isn't as impressive as the guys that made the cut.
This is tough. There are plenty of deserving players, and determining a fool-proof method for selecting them is particularly difficult. Closers like Joe Nathan and Grant Balfour are definitely deserving, but their peripherals aren't as impressive as the guys that made the cut. Alex Torres has been a force for the Rays, but Benoit gets the nod over him for more innings pitched and a superior win probability added (WPA). Given that Benoit has only been the Tigers closer for about a week, it's impressive that he is still third in the AL in WPA.
What about Drew Smyly? As good as he has been, he has been slightly outperformed by everyone else on the list. Cecil has filled a similar role out of the bullpen for the Blue Jays with a lower ERA, FIP, xFIP, and a higher WPA in just eight fewer innings.
Alright BYB, your turn. I took 36 players for 34 spots, just like the actual roster once the fan vote is completed. Who makes your roster?